1. Field of the Invention
The present invention relates to an image-forming apparatus employed in a printer and the like.
2. Description of the Prior Art
In a printer for example, an interval between a printing surface of a paper conveyed to a printing portion of a printing head and such printing portion is required to be maintained very closely to about 1 mm. However, if the printing surface of paper lifts or moves in a printing zone toward the printing head, printing is disturbed and thus the quality of printing cannot be guaranteed. Therefore, conveying means devices are arranged at the upstream and downstream sides, in a conveying direction of the paper, of the printing head so that printing occurs with the conveying devices maintaining the interval between the printing portion and the printing surface, and printing is finished immediately before conveyance of the trailing end of the paper by the upstream conveying device is released.
However, in such the paper conveying arrangement, a leading end portion of the paper before the leading end of the paper arrives at the downstream conveying device and a trailing end portion of the paper after conveyance of the trailing end of the paper by the upstream conveying device is finished are unable to be printed. That is, such portions are unprintable margins, and this situation is wasteful.
If it is attempted to print such portions by increasing the number of nozzles, the nozzle head becomes large sized due to the size of piezo-elements employed as ink pressure sources of the respective nozzles. Thereby, distances between the upstream conveying device and the printing head and between the downstream conveying device and the printing head are increased. Accordingly, the sizes of the unprintable margins are increased with an increase of the number of nozzles.
In a case where the paper to be printed is, for example, a so-called inter-office letterhead with a company name, company crest and the like printed on the leading end portion (or the trailing end portion) thereof, then printing at such portion is not required, although printing at the opposite end portion might be desired.